The present invention relates, in general, to brake cylinder apparatuses whereby both the service brake and the spring brake that is used for a parking brake, etc., are capable of operation, and, in particular, relates to a brake cylinder apparatus that can shorten the length of the axial direction.
In addition to the service brake apparatuses that act by compressed air in the platform car brake apparatuses used in railways cars, spring brake apparatuses that act by spring force are employed even when there is no compressed air in the event that one stops cars for a long period of time. When one makes this service brake apparatus and spring brake apparatus into a platform car brake apparatus that is independently installed separately, installation space becomes necessary.
Thus, a brake cylinder apparatus comprising both brake apparatuses in one unit has been developed such that an air brake apparatus and a spring brake apparatus can operate through the medium of the same piston rod.
For example, in Japan Public Patent Disclosure Bulletin S55-160646 (1980), as shown in FIG. 8, a brake cylinder apparatus with the following composition is disclosed: it is equipped with (a) a service brake means (91) that (i) possesses a first piston (93) wherein a rod (931) protrudes, and a first action chamber (94) and a first spring (95) act in opposition, and (ii) when a pressurized fluid acts on the first action chamber (94) the first piston (93) moves in the braking direction by overcoming the force applied by the first spring (95); (b) a spring brake means (92) that (i) possesses a second piston (98) wherein the rod (931) passes completely through, it has been provided such that it can move in the axial direction of the rod (931), and a second action chamber (96) and a second spring (97) act in opposition, and (ii) when a pressurized fluid stops acting on the second action chamber (96) the second piston (98) moves in said braking direction due to the force applied by the second spring (97), and a latch part (932) whereby the second piston (93) comes into direct contact with the rod (931) has been formed.
When the pressurized fluid acts on the first action chamber (94) of the service brake means (91), the first piston (98) and the rod (931) move in the braking direction in opposition to the first spring (95), and they end up in the service brake position shown in the figure. When the pressurized fluid stops acting on the first action chamber (94) of the service brake means (91) and the second action chamber (96) of the spring brake means (92) in this service brake position, the second piston (98) moves in the braking directing direction along the rod (931) due to the second spring (97). When this second piston (98) comes into direct contact with the latch part (932), the force applied by the second spring (97) is transmitted to the rod (931), and the spring brake acts in the place of the service brake.
In the event that a latch part (932) is formed on the rod (931) as in Japan Public Patent Disclosure Bulletin S55-160646 (1980), when the service brake means (91) is relaxed and the rod (931) is shortened by the force applied by the first spring (95), the latch part (932) has been provided by causing it to slide to the from end of the rod (931) so that the latch part (932) does not contact the second piston (98). Owing to this, it is necessary for the second piston (98) to move along the rod (931) by only the distance L shown in the figure, until the second piston (98) comes into direct contact with the latch part (932) of the rod (931). As a result, there is the problem that the length in the axial direction of the brake cylinder apparatus becomes longer by only a portion equivalent to the distance L.
In addition, in Japan Utility Model Disclosure Bulletin H08-5881 (1996), a brake cylinder apparatus with the following composition is proposed: a sleeve whereby one end can come into direct contact with the second piston (98), and the other end can come into contact with the step part of the large diameter part provided on the front end of the rod (931), has been fitted on the outer circumference of the rod (31), in the place of the latch part (932). However, since a sleeve whose length is such that it is possible to shorten the first piston (93) and the rod (931) can only be fitted on when the service brake means (91) is relaxed, it is necessary for the second piston (98) to operate an equivalent distance until the spring brake (92) is caused to operate, just as in Japan Public Patent Disclosure Bulletin S55-160646 (1980), and therefore there is the problem that the axial direction of the brake cylinder apparatus (90) becomes longer.
Thus, the present invention takes as its purpose the provision of the brake cylinder apparatus whereby both the service brake and the spring brake used as such things as a parking brake can operate, and at the same time it can shorten the length of the axial direction.
The invention in an embodiment that achieves the above-mentioned purposes is a brake cylinder apparatus characterized by the fact that, in a brake cylinder apparatus wherein both the service brake and the spring brake can move that is equipped with a service brake means that possesses a first piston wherein a rod protrudes. There is a first action chamber and a first spring act in opposition, and when a pressurized fluid acts on the first action chamber the first piston moves in the braking direction by overcoming the force applied by the first spring. A spring brake means that has a second piston wherein the rod passes completely through it, has been provided such that it can move in the axial direction of said rod. A second action chamber and a second spring act in opposition. When a pressurized fluid stops acting on the second action chamber the second piston moves in the braking direction due to the force applied by the second spring. A clutch means that couples the rod and the second piston when the pressurized fluid stops acting on the second action chamber and the second piston begins to move towards the rod has been provided.
Based on the above-mentioned composition, when the pressurized fluid stops acting on the second action chamber and the second piston begins to move towards the rod, the rod and the second piston are coupled by the clutch means, and the spring brake acts on the rod through the medium of the clutch means.
The invention in another embodiment is the brake cylinder apparatus composed such that the clutch means is equipped with a spring provided on one side of the rod or the second piston. A nut element is provided such that it can rotate freely on the other side of these. A stopping means stops the rotation of the nut element when the second piston begins to move towards the rod.
In the above-mentioned composition, when the rod of the first piston moves in the braking direction at the time of the action of the service brake, the nut element rotates, so the position of the second piston will not change. In addition, when the pressurized fluid stops acting on the second action chamber and the second piston begins to move towards the rod, the stopping means of the clutch means stops the rotation of the nut element, so the second piston and the rod become one, and move in the braking direction.
The invention of still another embodiment is the brake cylinder apparatus composed such that the stopping means is equipped with a sleeve element that is installed in a position opposing the nut element through the medium of a force application means, that can abrade freely in the axial direction of the rod, and whereby rotation has been stopped. A meshing means is provided on the surfaces opposing the sleeve element and the nut element, respectively.
In the above-mentioned composition, at the time of the action of the spring brake, when only the second piston moves in the braking direction while the nut element rotates, the meshing means of the nut element and the sleeve element mesh with each other, and the nut element becomes one with the sleeve element and the rotation is stopped.
The invention in yet another embodiment is the brake cylinder apparatus wherein the rotation of the sleeve means has been stopped by a lock means that can be attached and removed freely.
In the above-mentioned composition, during the action of the spring brake, when the lock means for the sleeve element is disconnected, the sleeve element and the nut element rotate, the rod can move in the anti-braking direction due to the force applied by the first spring, and the spring brake is released.
Another embodiment of the invention is the brake cylinder apparatus wherein the clutch means has been provided on the inner circumferential side of the second action chamber.
In this above-mentioned composition, the outer diameter of the second action chamber of an ordinary brake means becomes larger than the outer diameter of the first action chamber of the service brake means, so the sleeve element is provided by making use of the space of the inner circumferential side of this second action chamber.
The invention in another embodiment is the brake cylinder apparatus in which the first spring and the second spring have been installed such that they overlap in a diametrical direction.
In the above-mentioned composition, it is possible to make the service brake and the spring brake into one unit by shortening the length in the axial direction when the spring brake means and the service brake means are positioned by making them overlap in a diametrical direction.